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Woodsport Mk1 6 speed gearbox upgrade

Hi chaps, as per the title, i can provide you with a plug and play Mk1 6 speed gearbox conversion for your 4a-ge.

Is your 5 speed notchy?
Jumping out of fifth?
whining diff?
Lots of play on the driveshafts?
Crunching into gear?
Leaking oil?

Thinking about spending a lot of money on a recon gearbox?

Maybe now is the time to go 6 speed and bring your Mk1 up to date with a fresh gearbox at the same time.

What you get

I use a Celica Gen7 6 speed as the base donor gearbox, strip it right down, and refit the internals/gears into a Mk1b bellhousing (gives you two starter motor locations for use with either 16v or 20v swaps)

All gear cases are high pressure steam cleaned, new diff side bearings fitted to either your choice of stock C52 open diff or Mk3 Mr2 LSD unit.

The diff preload is then checked and adjusted methodically and reshimmed to the top end of Toyota spec.

The gears are all inspected, and new Toyota input shaft and output shaft bearings are installed.

The input shaft oil seal and both diff output oil seals are renewed.

The whole transmission is sealed and painted.

So you end up with a bearing and seal overhauled 6 speed gearbox that will bolt straight onto your 4a-ge engine without any modification whatsoever, your speedo cable will plug straight in, reverse light will plug in, driveshafts will work as normal with the Mk1 stock diff, all mountings will be OEM and the shifter assembly and slave cylinder will all just bolt up without any modification, truely plug and play. It will be a simple transmission swap no different than fitting another 5 speed.

If you request the LSD option then you will need to fit Mk2 NA driveshafts, but these are again plug and play into both the diff and Mk1 hubs without any mods.
The 6 speed will be carefully packed and shipped to your door within 2 weeks of ordering.
The gear ratios will be as follows...

This comes to £1030 , now there is often some discount to be had buying donor transmissions in bulk, i have four 6 speeds on their way this week alone, so i am advertising this at a delivered to your door price of £950 all in.

There is a company in the US that builds these for $4,500 each :shock:

If you want the LSD version you will need to add £250 to the above.

This is as cheap as a 6 speed Mk1 gearbox is ever going to get.

If you wish to send me your Mk1B gearbox as the donor i can knock £100 off the cost, please remember i cannot accept a Mk1A gearbox, its casing is not suitable for use. You can send me any Mk1B gearbox and it doesn't matter about its internal gears condition, we only use the bellhousing section.

If anyone has any questions i'm more than happy to answer, thankyou Paul.

TB Quote of the month:"I split my ear open whilst masturbating" - Jasper Full story Here

For those of us across the big pond and can't afford the shipping / customs taxes for your wonderful, professional quality solution, would it be possible to get the Celica C60 gearset + crown gear, Mk3 LSD and the extended end case from the C60? :)

Yes that will all work perfectly, the C60 internals and middle/upper cases will all fit to the Mk1b bellhousing, just make sure you use either the C60 bellhousing bearings or renew them, and if you don't reshim the diff preload it will eat itself in a few miles, other than that you're good to go.

TB Quote of the month:"I split my ear open whilst masturbating" - Jasper Full story Here

Stenky ordered one from me and wanted a few build pics, so i thought i'd do a mini build thread showing what is involved. I haven't included the work stripping the 6 speed box or the Mk1 box down to their component parts, this is just the new 6 speed Mk1 gearbox build up.

So we start with our Mk1b bellhousing, this has to be a Mk1b item, a Mk1a housing is not compatable with this conversion, you can identify a Mk1b gearbox because it has two starter motor locations on it, a Mk1a only has one. So this has been steam cleaned and degreased with all bearings removed.

This is all of the 6 speed internal parts from the donor C60 gearbox...

Here are all of the new bearings and seals from Toyota, nearly £400 worth, not a lot for the money but essential if this is to be done right.

This gearbox is getting the Mk3 LSD unit, so the first step is to remove the old bearings from the Mk3 LSD...

The Mk3 speedo cog is the same as a Mk1 cog, so the speedo will work as before.

Now install the new bearings onto the diff...

Now fit the 6 speed crownwheel onto the LSD, for the non LSD version you use the MK1 diff and Mk1 crownwheel which is also the same gear size but a different bolt PCD...

Now we fit the original diff washer into the case, this one is a fixed 2mm width, we adjust the preload on the diff by changing the thickness of the opposing shim in the other half of the case....

The new bearing race is then fitted...

Now we install the new output shaft bearing...

Not forgetting the retainer and bolt...

Now we fit the new input shaft bearing...

The adjustment shim is fitted to the middle case, this shim is what affects the load on the diff...

And the new race fitted over that...

This shim will need to come back out if the preload is not correct.

Now to adjust the preload we need to install both the diff and output shaft into the case...

The mid case is then dummy fitted and all bolts torqued down as it would be on the finished box, the top snap ring is also fitted...

A 14mm headed M10x1.25 bolt is screwed into the top of the output shaft so my torque meter can be used...

Rotating the meter reveals how much resistance there is on the new diff bearings, if it is too much then the case comes apart again, top shim replaced for a slightly thinner one and the case refitted again, this process is repeated until the correct diff preload is obtained. For info, 0.05 shim thickness results in 3.5 in/lbs of difference to the preload, the shims are available from Toyota in 0.05 increments.

Now that the preload is correct we can start to build the gearbox up properly starting with the input shaft and one of the selectors...

The rest of the selectors are then refitted...

Then three selector retaining bolts are fitted...

The lower selector detent ball and spring are now fitted....

Fit the case magnet...

Now time for the reverse selector...

The reverse idler is now added...

The shaft on this needs to be orientated correctly to the case or the retaining bolt on the outside won't line up...

Now the case is ready for sealant...

With the middle case fitted and all bolts torqued down for the final time, the reverse idler bolt can be fitted...

Now both snap rings are fitted to input and output shafts...

Add the shaft retainer plate and bolts..

Fit the selector circlip...

Install both upper selector detent balls/springs...

Now add 5th driven gear...

The roller bearing for 5th....

Refit the 5th/6th selector fork and synchro hub along with circlip....

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Tel: 0191 3770962 9am-5pm Mon-Fri Email : paul@woodsport.org

About Us

We used to be a pure MR2 engineering club but have since expanded our knowledge and interest to include pretty much anything that's 'retromod'. Taking already great machines and making them that little bit more special.